Some types of optical discs permit end users to optically write data on optically writable data surfaces of the optical discs. For example, users may be able to store data on the optical discs for later retrieval. Such data may include computer files, images, music, and other types of data. However, historically, users have had to label the optical discs using markers, which yields unprofessional results, or affix labels to the label sides of the optical discs, which can be laborious.
More recently, users have been able to form images directly on the label sides of optical discs, using optical discs that have optically writable label surfaces. The users employ optical disc devices that are able to optically write to such label surfaces of optical discs. For example, the previously filed patent application entitled “Integrated CD/DVD Recording and Label”, filed on Oct. 11, 2001, assigned Ser. No. 09/976,877, and published as US published patent application no. 2003/0108708, describes an optical disc having such an optically writable label surface.
Some types of optical discs having optically writable label surfaces have preformed or pre-imaged encoder spokes on areas of the optical discs. While such an optical disc is being rotated, the encoder spokes are detected so that the relative angular position of the optical disc currently incident to an optical mechanism that forms an image on the optically writable label surface of the optical disc is known. Employing encoder spokes to positionally control an optical disc while optically writing to the optically writable label surface of the optical disc can be disadvantageous, however.
The encoder spokes may not be able to be detected properly, due to the encoder spokes improperly interacting with other aspects of the optical discs. In some cases, forming the encoder spokes on optical discs raises the manufacturing costs of these optical discs. Detecting the encoder spokes can also require optical disc devices to have encoders and other hardware just for this purpose, raising their manufacturing costs as well. The encoder spokes further occupy relatively scarce space on optical discs that could otherwise be used for other purposes.